This segment contains a probable site of ubiquitination that ensures rapid degradation of tyrosine aminotransferase in rats. The half life of the enzyme in vivo is about 2-4 hours. In addition, unpublished information identifies at least 2 phosphorylation sites including CAPK at Ser29 and, at the other end of the protein, a casein kinase II site at S*QEECDK. This region of TAT is probably primarily related to regulatory events. Most other transaminases are much more stable and are not phosphorylated.